Programming the display

I seem to remember reading this somewhere, but now I can't find it.

I have mmap'ed 2000 bytes from /dev/display, but my changes do not appear on the hardware... what is the magic ioctl or other incantation to blit the new image to the display?

Also, how do I control the front status LED?

ioctl(fd,_IO('d',0));

should do the screen format conversion to the hoopy hardware memory layout for the screen. Your mmap'ed image is pretty standard left to right, top to bottom, 4bpp layout.

Screen on & off (and amp on/off, they're controlled by the same high-side-driver):

ioctl(fd,_IOW('d',1, int), state);
where 'state' is 1 or 0.

There are other calls used to deal with the screen buffering (you can buffer screens to lock them with the audio DMA) but this sort of stuff really needs proper documentation (ie, we're a bit busy at the mo!)

Hugo

Excellent.

I wrote some simple utilities to do screen captures and also to dump previous captures onto the display; I'm also writing a screen-dump-to-PNG converter so I can post images on the web.

Hugo, how do I toggle whether the LED is throbbing or steady?

This is a bit harder, involving me remembering how I programmed the PIC on the frontboard :)

When I work it out I'll tell you ;) I think it's to do with the state of LCD0 when the display is disabled: in one mode you have complete control from the main CPU, so you can make it do your own stuff under software control.

Hugo

What ioctl do I need to call, to turn the blinking standby LED off?



--
Raphael Wegmann
[email protected]